Relief valve that seals against vacuum

ABSTRACT

A relief valve that is reseatable to seal against high vacuum characterized by, in addition to the usual body and cap with conventional passageways, internal chamber, biasing means, and biasing adjustment means for effecting the relief valve action therewithin, a first resilient seat that is disposed circumferentially about a first passageway through the body and being designed to block flow in both directions when engaged by a seal surface; a first seat retainer removably holding the resilient seat in place and having a first annular seal surface; an upper seat reciprocally disposed within the internal chamber and having a seal surface at its lower end disposed adjacent the first resilient seat for sealing engagement therewith, the upper seat having a second annular seal surface disposed opposite the first annular seal surface; and a vacuum supplemental seal means for supplemental sealing against high vacuum. The vacuum supplemental seal means is disposed intermediate the first and second annular seal surfaces so as to sealingly engage them and block flow toward the first passageway when the upper seat has its seal surface sealingly engaging the first resilient seat. Thus, the relief valve can be employed as a safety release on a pressurized vessel, yet allow the vessel to be operated under high vacuum with a leak rate of only about 2 X 10 10 cubic centimeters per second.

. I h H Umted States Patent 11 1 [111 3,77, Turney Nov. 6, 1973 RELIEFVALVE THAT SEALS AGAINST VACUUM {57 1 ABSTRACT [75] Inventor: LarryTurney Demon A relief valve that is reseatable to seal against high vac[73] Assignee: Victor Equipment Company, uum characterized by, inaddition to the usual body and Demon, Tex. cap with conventionalpassageways, internal chamber,

biasing means, and biasing adjustment means for ef- [22] Filed 1972fecting the relief valve action therewithin, a first resil- [21] Appl.No.: 313,971 ient seat that is disposed circumferentially about a firstpassageway through the body and being designed to block flow in bothdirections when engaged by a seal [52] 11.8. Cl l37/5l6.25, 137/516.29,l2357l//524ld surface; a first Seat retainer removably holding the resilient seat in place and having a first annular seal sur- [51] Kurt.Cl. F16k 17/06 face an u er Seat reci mean dis Used within th 58 Fieldof Search 137/247.17, 247.19, PP y P ternal chamber and havmg a sealsurface at its lower 137/512, 512.3, 516.25, 516.29, 522, 526, d 05 dadacent th f St t tf 540, 543.17, 543.19; 251/172, 210, 211 e 1 e sea mgengagement therewith, the upper seat havlng a second 56] ReferencesCited annular seal surface d1sposed opposite the first annular 7 sea]surface, and a vacuum supplemental seal means-for UNITED STATES PATENTSsupplemental sealing against high vacuum. The vacuum 2,217,056 10/1940Johnson 137/526 supplemental seal means is disposed intermediate the2,557,536 1951 Dfane F 1 137/526 first and second annular seal surfacesso as to sealingly 2,809,659 10/1957 Glllesple et al. 137/526 engagethem and block flow toward the first passage 3058486 10,1962 McDerlnottet 137/51629 way when the upper seat has its sea] surface sealingly3,216,451 11/1965 Smallp1ece..... 137/516.25 th first res. m t Th th fIve 3,272,218 9/1966 Johnson 137/540 engag'ng e sea e "t 3,347,26610/1967 Hansen 137 540 can be emPkYed s a Safety release a PreSSUYZFd3,487,352 H1970 vessel, yet allow the vessel to be operated under hlghKikendall 137/540 Primary Examiner-William R. Cline Assistant ExaminerGeorge L. Walton Att0rneyWm. T. Wofford et a1.

vacuum with a leak rate of only about 2X10" cubic centimeters persecond.

4 Claims, 3 Drawing Figures 5/ RELIEF VALVE THAT SEALS AGAINST VACUUMBACKGROUND OF THE INVENTION 1. Field of the Invention:

This invention relates to a new type of valve not heretofore available;namely, a pressure relief valve that also seals against high vacuum.More particularly, this invention pertains to a pressure relief valvethat will reseat to hold high vacuum, even against the smallest, mostmobile, most difficulty sealed gaseous molecules.

2. Description of the Prior Art:

Myriad valve structures have been known to the prior art. These valvestructures have included relief valves, check valves, manually operableand automatically operable valves for sealing against a wide variety ofconditions.

Insofar as I am aware, however, the prior art has not provided acombination relief valve that would reseat I itself, even if actuated atthe high pressure, to seal against high vacuum; particularly sealingagainst even small, mobile, difficultly sealed-against gaseous moleculeslike helium. Consequently, researchers employing pressurized vesselsthat had to be subsequently evacuated to remove the contaminants within.the vessel have had to employ a plurality of valves, frequently usingdense metal seats and the like to seal against the small molecules underhigh vacuum.

Accordingly, it is an object of this invention to provide a combinationvalve that will serve both as a pressure relief valve and has a highvacuum valve that seals against even small, mobile gaseous molecules,thereby obviating the disadvantages of the prior art structures.

It is also a specific object of this invention to provide improvedstructural embodiments that effect the foregoing object, yet provide afool-proof valve that is easily assembled, economical and dependable.

These and other objects will become apparent from the descriptive matterhereinafter, particularly when taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS 'valve of FIGS. 1 and 2.

. DESCRIPTION OF PREFERRED EMBODIMENTS Referring to FIG. 1, the reliefvalve 11 is connected into an upper portion of a pressure vessel 13. Therelief valve 1 1 also is connected with conduit 13. The conduit 13 maylead to another vessel, or to an effluent element, such as a flare orhood, for safe venting ofthe fluids if the relief valve 11, is opened byhigh pressure. The relief valve 11 not only allows a release of fluid ifthe pressure in pressure vessel 13 becomes too high, but seals such thatthe pressure vessel 13 can be evacuated to remove contaminantstherefrom; for example, before it is filled with another gas, as forcarrying out a different reaction, or process step. Frequently, an inertgas such as helium will be employed in cleansing out vessels of othergaseous impurities by a process of alternate pressurization andevacuation. Thus, if conduit 13 is connected with another vesselundergoing such a purification, it is imperative that the relief valve11 seal against even the small helium molecules when the pressure vessel13 is evacuated to a high vacuum. It is imperative, for many scientificresearch projects that a leak rate of less than lXl0' cubic centimetersper second be achieveable under high vacuum operation; as forinvestigating heat transfer coefficients at high vacuum. The reliefvalve 11 has been found to efiect an unbelieveably low leak rate of onlyabout 2 l0' cubic centimeters per second under high vacuum operation.

Referring to FIGS. 2 and 3, the relief valve 11 comprises the majorelements andsubassemblies of body 17, cap 19, first resilient seat 21,first seat retainer 23, upper seat 25, biasing means 27, biasingadjustment means 29 and vacuum supplemental seal means 31.

The body 17 has a first passageway 33, FIG. 2, extending longitudinallythereof. The body 17 defines the bottom 33 of an internal chamber. Aconcentric, centrally disposed lip 37 is provided at the interior end ofthe first passageway 33 and affords interior concentric support for thefirst resilient seat 21. The body 17 has an internal thread 39 forconnection with the cap 19. If desired, O-rings may be employed inconjunction with the internal thread 39 to ensure sealing when apressurized interconnection is employed; as when conduit 13, FIG. 1,connects with another pressurized vessel. Ordinarily, the O-ring seal isnot necessary, since the conduit 13 is vented to the atmosphere. Thebody 17 has connection means, such as external threads 41, for beingconnected with a vessel that is capable of withstanding both thepressure and vacuum, illustrated by pressure vessel 13 in FIG. 1.Expressed otherwise, the relief valve 11 is sealingly screwed into areinforced top 33 of pressure vessel 13.

The cap 19 sealingly engages the body 17 to define an internal chamber43, FIG. 2. Specifically, the cap 19 has an exitemal thread 47 thatsealingly engages the intemal thread 39 of body 17. As indicatedhereinbefore, the degree of sealing is not ordinarily critical. The cap19 has a second passageway 39 leading exteriorly thereof. Asillustrated, the second passageway 49 leads into an internally threadedsection 31 that may be employed for connection with a conduit, such asconduit 13, to vent any fluids released to a safe area. The internalchamber. 33 is connected with the first passageway 33 at one end, nearthe bottom 33. The internal chamber 33 is connected with the secondpassageway 49 at adjustment means 29.

The first resilient seat 21 is disposed circumferentially about thefirst passageway, as annularly about'lip 37. The first resilient seat 21has a coefficient of elasticity, has a modulus of compressibility and isdesigned so as to block flow of fluids in both directions when engagedby a seal surface. Specifically, the first resilient seat 21 comprises aTeflon ring that has rounded top shoulders 33. The Teflon has therequisite modulus of compressibility and coeffeicient of elasticity; andthe rounded annularly disposed, top shoulders 33 serve to block fluidflow in both directions when engaged by a flat seal surface, such asseal surface 37 on the upper seat 23. The top shoulders 33 protrudeinteriorly of the internal chamber 43 beyond the lip 37. When the sealsurface 37 exerts pressure on the top shoulders 33,

there is sealing engagement. The force with which the top shoulders 55resist further downward movement of the seal surface 57 is increased bythe support given by interiorly disposed lip 37 and the exteriorlydisposed first seat retainer 23. Other materials, such as nylon, can beemployed for the resilient seat 21 instead of Teflon. It should beemphasized, however, that the material of which the first resilient seatis made must have elasticity sufiicient to rebound after prolongedclosure, must have sufficient rigidity to sealingly engage the sealsurface 57 with a force great enough to retain pressure within thevessel 13, and must be inert to the fluids that would be employed in thevessel 13 so as to resist deterioration.

The first seat retainer 23 is disposed circumferentially of the firstresilient seat 21. The first seat retainer 23 is rigid so as to providethe requisite strength in back-up of the first resilient seat 21; and,also, to provide a seal surface for forming a second, or supplementary,seal. Ordinarily, the first seat retainer 23 will be formed of metal,such as the copper alloys or stainless steels. The first seat retainer23 is removably retained in the body 17. As illustrated, its top engagesthe bottom of the internal threaded section of the cap 19 so as to holdthe first resilient seat 21 in place when the cap 19 is screwed into thebody 17. As illustrated, also, the first seat retainer 23 has a firstannular seal surface 61. The first annular seal surface 61 is in theform of a frusto-conical section that has a surface that is sufficientlysmooth to effect sealing when engaged by the vacuum supplemental sealmeans 31. The first seat retainer 23 has a centrally disposed aperture63 that allows the sea] surface 57 on the bottom of upper seat 25 tocome in contact with the top shoulders 55.

The upper seat 25 is reciprocally disposed within the internal chamber45. Expressed otherwise, the upper seat 25 is movable longitudinally andreciprocally within the chamber 45, although it has only slightlysmaller outside dimensions than the chamber 45 has inside dimensions. Asindicated hereinbefore, the upper seat 25 has seal surface 57 at its enddisposed adjacent the first resilient seat 21 for sealing engagement Itherewith, normally its lower end when installed in an upright position.As illustrated, the seal surface 57 is disposed at the bottom end of acentral protrusion 65 that fits within the centrally disposed aperture63 of the first seat retainer 23. The upper seat 25 has a pivot fulcrum67 that protrudes interiorly within a cavity 69. The cavity 69 and theprotrusion 67 will be described in more detail with respect to thebiasing means 27 hereinafter. The upper seat 25 has a second annularseal surface 71 that is disposed opposite and closely adjacent the firstannular seal surface 61 for sealing engagement with the vacuumsupplemental seal means 31 when the upper seat is in its closedposition. The closed position is defined by sealing engagement of theseal surface 57 with the top shoulder of the first resilient seat 21.Specifically, the annular seal surface 71 is an inverted frusto-conicalsection.

The biasing means 27 is provided for biasing the upper seat 25 towardits closed position. As illustrated, the biasing means 27 comprisesspring 73, pressure internal chamber 45. The bottom of the spring 73 andthe rocking plate 77 are disposed interiorly of the cavity 69 within theupper seat 25. The pivot fulcrum 67 and the rocking plate 77 accommodateimperfections 'plate 75 and rocking plate 77, all disposed within the inthe spring 73 and allows the use of economical imperfect springs as thebiasing means 27.

The biasing adjusting means 29 comprises an adjustment screw within theinternally threaded aperture 53. A cap nut 79 is provided to cover theallen head socket 81 in the adjustment screw and to lock the adjustmentscrew at a setting. The cap nut 79 may be removed and an allen headwrench inserted in the allen head socket 81 to increase the compressiveforce and consequently increase the pressure at which the relief valvewill vent fluids from the pressure vessel 13. Conversely, screwing thebiasing adjustment means 29 in the opposite direction will decrease thecompression on spring 73 and decrease the pressure at which the reliefvalve 11 will vent fluid. The cap nut is reinstalled to lock in the newsetting.

The vacuum supplemental seal means 31 is provided for additional andmore nearly perfect sealing against high vacuum. The vacuum supplementalseal means 31 is disposed intermediate the first and second annular sealsurfaces 61 and 71 so as to sealingly engage them and block the flow offluids toward the first passageway 33 when the upper seat 25 has itsseal surface 57 sealingly engaging the first resilient seat 21. Asillustrated, the vacuum supplemental seal means 31 is an O-ring thatsealingly engages the respective frusto-conical annular seal surfaces 61and 71 with progressively greater force under progressively greatervacuum differential pressure.

In operation, the relief valve 11 is screwed into the pressure vessel 13and the biasing adjustment means 29 screwed down to attain the desiredcompression on the biasing means 27 to control the pressure againstwhich the relief valve 11 will relieve pressure. Assume that pressure isreached, the pressure against the protrusion 65 will force the upperseat 25 upwardly allowing fluid to flow intermediate the seal surface 57and the top shoulders 55. The fluid will also flow intermediate thevacuum supplemental seal means 31 and its respective opposed annularseal surfaces 61 and 71 and out the second passageway 49. When pressureis relieved, the valve will reseat under the force of the spring 73,again sealingly engaging the seal surface 57 with the top shoulders 55.Thereafter, a vacuum may be drawn on pressure vessel 13, as forcleansing of the gas that previously occupied its interior. Initially,the first resilient seat 21 forms an adequate seal with the seal surface57. As is well known in the art, however, the problem of sealing againsthigh vacuum is inexplicably difficult. Consequently, as higher vaccumsare attained, there will be, ordinarily, a propensity for a valve sealto leak. In the event there is leakage intermediate the top shoulder 55and the seal surface 57, the vacuum supplemental seal means 31'is drawninto sealing engagement with its respective and oppositely disposedannular seal surfaces 61 and 71 to seal thereagainst with anincreasingly greater force as the vacuum becomes increasingly greater.In this way, the surprisingly low leak rate is attainable under vacuum.

From the foregoing, it can be seen that this invention attains theobjects delineated hereinbefore, provides a surprising relief valve thatserves as a combination relief valve and vacuum-proof valve to sealagainst high pressure within a pressure vessel or against high vacuumwithin the pressure vessel. In fact, the relief valve ll has enabledattaining an unbelieveable low leak rate of 2 10" cubic centimeters persecond. This leak rate is much less than the 1X 1 0* cubic centimetersper second needed and heretofore thought unattainable in a single valvethat also serves as a pressure relief valve.

Although this invention has been described with a certain degree ofparticularlity, it is understood that the present disclosure has beenmade only by way of example and that numerous changes in the details ofconstruction and the combination and arrangement of parts may beresorted to without departing from the spirit and the scope of thisinvention.

What is claimed is:

l. A relief valve that is reseatable to seal against vacuum comprising:

a. a body having a longitudinally extending first passageway and havinga connection means for being connected with a vessel that is capable ofwithstanding both pressure and vacuum;

b. a cap sealingly engaging said body to define an internal chambertherewithin and having a second passageway extending exteriorly thereof;said internal chamber being in connection with said first passageway atone end and with said second passageway at a location spaced from saidone end;

0. first resilient seat disposed circumferentially about said firstpassageway; said first resilient seat having a coefficient of elasticityand a compressive strength sufficient to, and being adapted so as to,block fluid flow in both directions when engaged by a seal surface;

01. a first seat retainer disposed circumferentially of said firstresilient seat and having a first annular sea] surface; said first seatretainer being removably retained in said internal chamber;

. upper seat reciprocally disposed within said internal chamber; saidupper seat having a sea] surface at its one end disposed adjacent saidfirst resilient seat for sealing engagement therewith; said upper seathaving a second annular sea] surface disposed opposite said firstannular seal surface;

f. biasing means for biasing said seal surface of said upper seat towardsaid first resilient seat;

g. biasing adjustment means for adjusting the force with which saidupper seat is biased toward said first resilient seat; and

h. vacuum supplemental seal means for supplemental sealing against highvacuum; said vacuum supplemental seal means being disposed intermediatesaid first and second annular seal surfaces so as to sealingly engagesame and block flow toward said first passageway when said upper seathas its seal surface sealingly engaging said first resilient seat suchthat said relief valve can be employed as a safety release against highpressure within said vessel and still have a leak rate less than 1X10cubic centimeters per second under high vacuum following pressurizedoperation.

2. The relief valve of claim 1 wherein said first resilient seatcomprises a Teflon ring that has a top cross sectional shape that isarcuate at its top shoulder for engaging a flat seal surface and whereinsaid seal surface on said upper seat is flat.

3. The relief valve of claim 1 wherein said first and second annularseal surfaces comprise smooth, opposed frusto-conical and invertedfrusto-conical surfaces; and said vacuum supplemental seal meanscomprises an ()-ring that sealingly engages respective saidfrusto-conical seal surfaces with progressively greater force underprogressively greater vacuum differential pressure such that a leak rateof about 2X10 cubic centimeters per second is attainable even at nearperfect vacuum.

4. The relief valve of claim ll wherein said biasing means is aneconomical spring and said upper seat contains a centrally disposedpivot fulcrum at its one end; and a rocking plate is disposedintermediate said pivot fulcrum and the end of said spring such that aneconomical and imperfect spring can be employed; and said biasingadjusting means comprises an adjustable screw for increasing anddecreasing the compressive force on said spring.

i l l l W

1. A relief valve that is reseatable to seal against vacuum comprising:a. a body having a longitudinally extending first passageway and havinga connection means for being connected with a vessel that is capable ofwithstanding both pressure and vacuum; b. a cap sealingly engaging saidbody to define an internal chamber therewithin and having a secondpassageway extending exteriorly thereof; said internal chamber being inconnection with said first passageway at one end and with said secondpassageway at a location spaced from said one end; c. first resilientseat disposed circumferentially about said first passageway; said firstresilient seat having a coefficient of elasticity and a compressivestrength sufficient to, and being adapted so as to, block fluid flow inboth directions when engaged by a seal surface; d. a first seat retainerdisposed circumferentially of said first resilient seat and having afirst annular seal surface; said first seat retainer being removablyretained in said internal chamber; e. upper seat reciprocally disposedwithin said internal chamber; said upper seat having a seal surface atits one end disposed adjacent said first resilient seat for sealingengagement therewith; said upper seat having a second annular sealsurface disposed opposite said first annular seal surface; f. biasingmeans for biasing said seal surface of said upper seat toward said firstresilient seat; g. biasing adjustment means for adjusting the force withwhich said upper seat is biased toward said first resilient seat; and h.vacuum supplemental seal means for supplemental sealing against highvacuum; said vacuum supplemental seal means being disposed intermediatesaid first and second annular seal surfaces so as to sealingly engagesame and block flow toward said first passageway when said upper seathas its seal surface sealingly engaging said first resilient seat suchthat said relief valve can be employed as a safety release against highpressure within said vessel and still have a leak rate less than 1 X 109 cubic centimeters per second under high vacuum following pressurizedoperation.
 2. The relief valve of claim 1 wherein said first resilientseat comprises a Teflon ring that has a top cross sectional shape thatis arcuate at its top shoulder for engaging a flat seal surface andwherein said seal surface on said upper seat is flat.
 3. The reliefvalve of claim 1 wherein said first and second annular seal surfacescomprise smooth, opposed frusto-conical and inverted frusto-conicalsurfaces; and said vacuum supplemental seal means comprises an O-ringthat sealingly engages respective said frusto-conical seal surfaces withprogressively greater force under progressively greater vacuumdifferential pressure such that a leak rate of about 2 X 10 10 cubiccentimeters per second is attainable even at near perfect vacuum.
 4. Therelief valve of claim 1 wherein said biasing means is an economicalspring and said upper seat contains a centrally disposed pivot fulcrumat its one end; and a rocking plate is disposed intermediate said pivotfulcrum and the end of said spring suCh that an economical and imperfectspring can be employed; and said biasing adjusting means comprises anadjustable screw for increasing and decreasing the compressive force onsaid spring.